Uric acid stimulates endothelin-1 gene expression associated with NADPH oxidase in human aortic smooth muscle cells.
OBJECTIVE
Recent experimental and human studies have shown that hyperuricemia is associated with hypertension and cardiovascular diseases. Elevated levels of endothelin-1 (ET-1) has been regarded as one of the most powerful independent predictors of cardiovascular diseases. For investigating whether uric acidinduced vascular diseases are related to ET-1, the uric acid-induced ET-1 expression in human aortic smooth muscle cells (HASMC) was examined.


METHODS
Cultured HASMC treated with uric acid, cell proliferation and ET-1 expression were examined. Antioxidant pretreatments on uric acid-induced extracellular signal-regulated kinases (ERK) phosphorylation were carried out to elucidate the redox-sensitive pathway in proliferation and ET-1 gene expression.


RESULTS
Uric acid was found to increase HASMC proliferation, ET-1 expression and reactive oxygen species production. The ability of both N-acetylcysteine and apocynin (1-[4-hydroxy-3-methoxyphenyl]ethanone, a NADPH oxidase inhibitor) to inhibit uric acid-induced ET-1 secretion and cell proliferation suggested the involvement of intracellular redox pathways. Furthermore, apocynin, and p47phox small interfering RNA knockdown inhibited ET-1 secretion and cell proliferation induced by uric acid. Inhibition of ERK by U0126 (1,4-diamino-2,3-dicyano- 1,4-bis[2-aminophenylthio]butadiene) significantly suppressed uric acid-induced ET-1 expression, implicating this pathway in the response to uric acid. In addition, uric acid increased the transcription factor activator protein-1 (AP-1) mediated reporter activity, as well as the ERK phosphorylation. Mutational analysis of the ET-1 gene promoter showed that the AP-1 binding site was an important cis-element in uric acid-induced ET-1 gene expression.


CONCLUSIONS
This is the first observation of ET-1 regulation by uric acid in HASMC, which implicates the important role of uric acid in the vascular changes associated with hypertension and vascular diseases.
Chao
Hung-hsing
HH
Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan, China.
Liu
Ju-chi
JC
Lin
Jia-wei
JW
Chen
Cheng-hsien
CH
Wu
Chieh-hsi
CH
Cheng
Tzu-hurng
TH
D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D019332:Endothelin-1 / Q000096:biosynthesis* / Q000235:genetics*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D019255:NADPH Oxidases / Q000502:physiology*; D012313:RNA / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013268:Stimulation, Chemical; D014162:Transfection; D014527:Uric Acid / Q000494:pharmacology*
D019332:Endothelin-1; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D014527:Uric Acid; D012313:RNA; D019255:NADPH Oxidases; D015500:Chloramphenicol O-Acetyltransferase; D048049:Extracellular Signal-Regulated MAP Kinases